Separating and mixing apparatus



June 17, 1930. E. FALKENTHAL SEPARATING AND MIXING APPARKWS Filed 1923 wit - humid June 17, 1930 UNITED sTMEs PATENT OFFICE Application filed October 4, 1923, aerial No. 866,608, and in. Germany April 28,1921.

This invention relates to separating apparatus and more particular] to apparatus for separating foreign partic es from a flowing stream, such as air, gases or Va ors, or liquid, and collectin the same for t e purpose of purifyingt e said stream, and'for avoiding loss of valuable substances in industrial processes. I

The invention has for its ob 'ect a separation of a novel kind, whereby the oreign particles sus ended in a flowing stream are settled outthe aid of filtering water, as heretofore used in separating dust from air or gas, and-without precipitating water, as heretofore used in separating oil from vapor, but only by leading-in the streamv with a low speed offlow, for instance of about 1 mm. er

sec.,'into a compartment closed by a very t invertical grid, and passing the said stream with the particles suspended therein through the said grid and through a whirling-zone which is roduced on the rear side of the grid, the d iist settling action not taking place on the front side of the grid but on the rear side thereof within the whirls of the said whirling-zone. The separated matter is in all cases not water, but a solid, or another liquid.

For producing the said whirling-zone the grid is formed of a thin sheet, preferably of metal, and is provided with numerous openings which have no projectin sharp edges and a minimum dimension 0 about three to ten times the grids thickness; these 0 enings, further, having a distance apart rom each other equal to the said maximum dimension of an opening, and therefore each producing a flat whirling behind itself on the rear side of the grid. In consequence of this arrangement the rear side of the grid is covered with numerous confining whirls which have a uniform distribution corresponding to the distribution of the grid openings and formin a flat whirling zone wherein the settling e ect takes place.

To ascertain whether the whirls are pro-.

duced in the'desired scope, a sample of the grid intended to be used is laced with its rear side near a flame. On the stream passing through the grid the flaring flame should show a distinctly defined whirling zone at the rear of the grid, which is confined sharpl to a slow stream going away from the grid: In the case of liquids the whirling effect can be observed by means of admixtures of color or powder.

An effective grid for the urpose'of this invention can for example, be produced by punching or boring holes in a metal sheet, while a web woven of round wire would be entirely ineffective. However, a round wire grid can be adapted for thespurpose of this invention b flattening the same by rollers to produce s arp edged meshes. It is to be noted that the openings must not have the form of channels whoselength exceeds their diameter, or of funnels whose diameter decreases toward one end thereof.

In practice the openings in the grid will have a minimum diameter of about 0.3 mm. in a sheet of about 0.03 mm. thickness up to a minimum diameter of about 3 of about 1 mm. thickness.

The distance apart from each other of the openings mustv be such that there exists between adjacent openings asolid imperforate gridarea substantially equal to the area of one adjacent opening. According to this principle, in the case of slit-like a'nd arallel arranged openings, the solid strip etween each two slits must be at least as broad as the width of a slit. f

For the purpose of the invention the width of the sharp-edged openings of the grid must be such that the grains of dust (or drops of oil or the like) are not obstructed in their passage through the openings or meshes. The width of the openings may amount to -100 times the size of the grains or drops. An opening greater than about 10 mms. will hardly ever be necessary. A greater speed of flow will generally require a smaller width of.opening.-

In the whirls, which form chiefly at the rear of the grid but also to a; smaller degree at thefront of the same, an agglomeration of the dust suspended in the flowing substance of the stream takes place, so that it is caused to drop b gravity, and to accumulate at the bottom 0 the casmg. Some of the dust particles impinge upon the lands between the mm. in a sheet openings in the grid, and accumulate there until the drop automatically or are removed by suita le instruments, such as brushes, scrapers, vibrators or the hire, or by washing or sprinkling. The agglomeration of the particles seems to be accompanied by electrical effects, for it is observed that the grids become charged with electricity. Apparently the friction of the dust particles against the sharp edges of the openings and their mutual friction in the whirls cause the particles to be electrically charged.

The total area of the openings of the grid depends upon the speed of the flowing stream sent through it, and should be such that a throttling action or an obstruction of flow is avoided as much as possible. By increasing-the cross-sectional area of the casing in comparison with the cross section of the leading-in pipe by which the stream is conducted into the casing the speed of flow at the grid canbe reduced to any desired extent. It has been found in practice that in most cases the most favorable results are obtained at a speed of one meter per second. At this speed the difference of pressure between the front and rear sides of the grid with slit-shaped openings 1 mm. in width and which occupy a out one-third of the grids surface, corresponds to a pressure of a column of water not over 1 to 2 mm. high. A grid of this kind used for the separation of dust extracts about of the dust, such as lime particles, suspended in flowing air. If four grids of this kind are placed one behind the other the amount of dust particles extracted is or more.

The percentage of dust or moisture particles'separated at a rid depends largely u on the number of w irl-producing edges 0 the openings present in a-unit of surface. For this reason the openings are preferably formed as above mentioned, in the shape of narrow slits ofa width of one-half to ten mms. arranged parallel to each other. Round openings are generall not quite as effective, slit formed openings being the kind preferred for the extraction of fine dust. Dust of the kind which could not be extracted hitherto by means of known forms of dust extractors, such as brown coal or calcareous dust, can be extracted by grids according to this invention provided with slit-shaped o enings.

The grid is to bearrange in a vertical position and the slits are preferably disposed in vertical rows. The solid grid-area left between the rows of slits will then form quiescent precipitating zones at the rear of the grid for the dust that passes out from the whirling zones.

When several ids are arranged behind one another, the ree space left behind each grid may be reduced so that it is only sufiicient to provide room for the whirling zones, or order to reduce the length of the separating apparatus as far as possible. The width of 10 cms. The number of grids arranged one behind another for the purpose of separating the greatest possible amount of foreign particles will increase with the speed of flow and the width of the slits compared to the size of the particles to be extracted. When a plurality of grids are placed behind one another theopeningsiftlfi difirentgrids need not differ in size because, in the devices according to this invention, it is not a question of sifting out particles of increasing fineness. The number of openings in the different grids may, however, increase from the first to the last grid while their size decreases, so that the total area of the openings on each grid is the same.

A particular advantage of this invention is that large pacifying spaces are not required, as in known dust separators, in which the dust is allowed to sink automatically, and for this reason the novel separators according to this invention are to be preferred wherever separators of the ordinary kind would'take up too much space.

The effect of separators with a plurality the waste steam of steam engines.

In the case of gases or liquids which attack metal the grid is made from bakelite or similar artificial substances which permit of sharp edged openings being made therein. The openings are produced by stamping, milling or drilling.

The dust separating effect my be further intensified by charging the grids with electricity as in the Cottrell process, this device being particularly applicable in the case of air containing only a little dust. This method is also particularly advantageous when dust injurious to health or dust containing valuable solids is to be dealt with. A substitute for electrically charging the grid consists in the use of a filtering cloth placed around the last grid in a series, which cloth only serves to remove the last traces of dust, and therefore remains effective for a long time.

In some cases it will be found advantageous to moisten the dust separating grid with oil or other adhesive substances 1n order. to catch the finest dust.

In the apparatus for separating dust or moisture the stream is conducted into one end of the grid container and let out from the other. The dust or condensed moisture is deposited in the individual compartment! between. the grids from which it is removed from time to time byopening the apparatus, or continually conducting it ofi. i Another field of application is in the production of dried egg or milk. Hot air containin s rayed milk or egg is guided throug the rid and dried substance is separated on t e rear side of the grid. The invention is illustrated in the accomm panying drawing, in which- Fi ure 1 shows my dust separator of the simplest form.

Fig. 2 illustrates a dust separator of a combined grid arran ement with dustremoving fittings and oading electrodes.

Fig. 3 is a fra ment of a grid from the dust remover of 1 1g. 1 or 2 in natural size.

' Fig. 4 is a cross section of the dust remover according to Figure 2.

The apparatus shown in Fig. 1 consists of a casing in theform of two frustums connected at their widest parts by a short cylinder, the narrow ends of the frustums having pipes a, b, and the middle cylindrical portion being fitted with a pipe 0. At both ends of the cylindrical portion grids G, G are placed. The air or gas to be purified is led in through the pipe at or gas is let off through so sage of the air or gas the pipe I). The pasthrough the grid G,

' causes them to form whirls 1n the cylindri cal portion of the casing behind the grid G The dust settled within these whirls is drawn ofi periodically or continually through the aspi ec.

ig. 2 illustrates a dust remover consisting of a hollow cylinder a which is provided with a lateral pipe I) and fitted at the top 23 and bottom w1th hollow truncatedcones d, e to which are connected pipes f, g. The casing contains four curved grid-walls 72. formed by the windings of a spirally wound grid-band, for instance as is shown 1n Fig. 4. The grid walls have vertical rows of. slits, as shown in Fig. 3. The land 11 between the slits is about equal in width to the length of a slit, so that the surface area of a row of slits is about equal to the area of the land In between the rows. The land or unperforated strip may generally bemade somewhat wider sa up to 1. 5 the width of a row of slits. T e dust separator illustrated may be used for separating calcium nitrate or nitrite, for example. At their bottom edges the grid-walls are attached to hollow frustums m upon which the dust collects and slides downwards. These frustums m prevent the air current from evading the grids. The frustums may also be perforated in order to equalize the accumulation of dust upon them.

Dust-laden air is injected. through the pipe f and passes through the grid-walls one after the other, as indicated by the arrows, the air being thus caused to deposit its dust, which 66 latter falls through the pipe 9 into a dust are indicated at r.

and the purified air collector, whilst the purified air is conducted ofi through a pi e b. A grid n, also slitted as indicated in 3 prevents the current of air which isinjectedat f from whirling up the dust that slides down in the frustums. m. In the space between is arranged-a conveyor worm o, for preventng clogging in cases where dust is deposited 1n arge quantities. The bearings fortheworm he worm o is motordrlven by shaft q which is held in bearings r of suitable spiders, giving a broad passage for the dust. The outermost grid is surrounded by a filterin cloth 1) of the kind h'ereinbefore mentioned.

In Fig. 2 the height ofthe c increases as their diameter ecreases. advantageous to make thisincrease such that all the grids will have substantially the same area. This is for the purpose of makin the speed of flow at the grids of different iameter approximately equal, which in certain cases tends to improve the dust separating effect.

In Fig. 2 is also shown a set of electrodes consisting of wires 10 which depend from the cover t o the ap by weights 1). he wires are insulated from the cover it by insulatingknobs w, and, as indicated,'are all connected with the positive side of a battery, the negative side of the same being connected with the cover 25. These electrodes are arranged for the purpose of creating an electrostatic dust-settling field, as already stated.

Between the windings of the spiral grid (Fig. 2), brushes may purpose of preventing clogging of the grids. In the interior of the innermost grid a stirring device may be arranged, which is adapted to pass on the dust that collects there to the conveyor worm.

It is thus seen that by an appropriatev application of the invention, apparatus can be constructed by which gases or liquids containin foreign particles insusgension may be per f ectly separated and puri ed in a simple and highly eflicient manner.

I claim 1. In an apparatus for settling foreign particles of dust-size from flowing matter, in combination: a compartment arranged for being passed through by the flowing matter, a vertical grid forming a wall of said compartment and arranged for being passed through by the same flowing matter, the grid consisting of a very thin sheet, preferably of metal, and having numerous equally sized sharp edged openings, said openings having no projectin sharp edges and being a distance apart rom each other equal with the minimum dimension of an opening, said distance being measured in the direction of said dimension, the grid bein thus enabled for producing on its rear si e a whirling zone the frustums' m there' lindrical grids It is be arranged for the aratus and are held straight of uniform thickness in the flowing matter, means bein provided for collecting the foreign partic es falling down behin the said grid from the said whirling zone.

2. In an apparatus for settling foreign particles of dust-size from flowing matter, in combination: a compartment arranged for being passed through by the flowing matter, a vertical grid forming a wall of said compartment and arran ed for being passed through by the same owing matter, the grid consisting of a very thin sheet, preferably of metal, and having numerous slit-formed, equally sized, sharp edged openings, these shts being disposed parallel with one another in vertical rows which are separated by solid strips of grid area, the said slits having a minimum dimension of about two to ten times the thickness of the sheet and having no projecting edges, the distance apart between each two slits in the same row being equal to the minimum width of a slit, the grid being thus enabled for producing on its rear side a whirling zone in the flowing matter, means being provided for collecting the foreign particles falling down in quiet zones which exist hind the said solid area strips.

3. In an apparatus for settling foreign particles of dust-size from flowing matter; a plurality of wall portions arranged for being passed through in series by the flowing matter and consisting of portions of a vertical grid, the grid consisting of a very thin sheet, preferably of metal, and having numerous equally sized sharp edged openings with a minimum dimension of about two to ten times particles of dust-size from the thickness of the sheet, the said openings having no projecting edges, and the distance apart of the openings-from each other being equal with the said minimum dimension measured in the direction of said dimension, the grid being thus enabled for producing on its rear side a whirling zone in the flowin matter, means being provided for collecting the foreign particles falling down behind said grid from the said whirling zones.

4. In an apparatus for settling foreign flowing matter; a vertical, spiral grid, the rid decreasing in height from the first to theflast turn and consisting of a very thin sheet, preferably of metal, and havin numerous equally sized sharp edged openings with a minimum'dimension of about two to ten times the thickness of the sheet, the said openings having ,no projecting edges and the distance apart from each other being equal to the said minimum dimension of an opening measured in the direction of said dimension, said grid being thus enabled for producing on its rear side a whirling zone in the flowing matter, means being provided for collecting the foreign particles falling down behind the said grid from the said whirling zones.

5. In an apparatus for settling foreign particles of a dust-size from flowing matter" a vertical, spiral grid, the said grid an spaces between its turns being arranged for being passed through in series from. inwardly to outwardly, or vice versa, by the flowing matter, the said grid consisting of a very thin sheet, preferably of metal, and having numerous equally sized sharp edged openings with a minimum dimension of about two to ten times the thickness of the sheet, the said openings having no projecting edges and being a distance apart from each other equal with said minimum dimension of an opening measured in the direction of said dimension, said grid being thus enabled to produce on its rear side a whirling zone in the flowing matter, frustum-shaped walls extendin from the bottoms of said turns of the gri and a conveyor worm arranged within the axis of the spiral for conducting away the foreign particles falling down from the whirling zones.

6. In an apparatus for settling foreign particles of dust-size from flowing matter; a vertical, spiral grid, said grid consisting of a very thin sheet, preferably of metal, having numerous equally sized sharp edged openings with a minimum dimension of about two to ten times the thickness of the sheet, the said openings having no projecting edges and being a distance apart from each other equal to the said minimum dimension measured in the direction of said dimension, the grid being thus enabled to produce on its rear side a whirling zone in the flowing matter, means being rovided for collecting the foreign particles alling down behind the said grid from the said whirling zones, a plurality of electrodes beingarranged in each of the spaces between adjacent turns of the spiral for creating electrostatic dust settling fields.

In testimony whereof I have aflixed my signature.

' ERWIN FALKENTHAL.

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